Why marketing must partner sales

I have had the good (!) fortune of being on both sides of the great sales and marketing divide in B2B S&M organizations. When in marketing, the lament was how all efforts go to waste because sales "does not follow through and close the leads we generated" and in my stints in sales, I was convinced that "marketing is clueless"- about the market, about customers and their needs. Their leads were of no use to me. It was as if our goals and priorities were different.
The truth is that in large B2B companies, local marketing in countries are focused on the heavy-lifting; running trade-shows, sending out mailers, placing ads. The accent is on getting things done rather than genuinely trying to listen to customers and integrate their feedback into the product or service introduction process.
So, marketing runs programs with no feedback loops. Any customer response, howsoever "raw" is passed on to sales as a "lead". There is no way of telling a good lead from a bad one and since "lead-nurturing" as a concept does not exist; sales essentially starts working with a prospect who is at the very early stage of awareness.
What is the solution? Marketing and sales need to work together on an acceptable definition of a lead. This will vary from industry to industry and company to company but the agreement needs to happen so that marketing can work to create programs that nurture the raw leads further and pass on leads that interest the sales. On their part, sales could do more to spot the micro-trends in their industries, the customer pain-points and decision making roles in client organizations and log them formally. This will help marketing to create programs that address the right customer problems, identify the right solutions and target the right communication to the right customer contacts involved in purchase.